In 2009, Abel Maldonado, then a state senator, brought the top-two open primary to California. The change allowed the two leading finishers in a primary to proceed to the general election regardless of party affiliation. It set into motion a system that would reshape the state’s politics.

Today, Maldonado is as much vilified as lauded in the state, but he is supremely satisfied with what he did. “You know what, you get a little lazy sometimes, and with a closed primary system, where you keep independents from voting, let me tell you something, you can be lazy,” he told me. “With this open primary, you have to work for the taxpayers.”

In an open primary, people vote for any candidate regardless of party affiliation. But in California, a top-two primary system paved the way for two candidates of the same party to confront one another in the general election. As a result, political parties are no longer guaranteed a spot in the general, nor can they dispense with moderates within their own party in a primary election. Louisiana and Washington are the only two other states that have adopted such a system.

In 2009, California’s state legislature was struggling to pass a budget. Republicans dug in their heels because the Democrats’ budget contained a massive tax hike, going against a pledge signed by many GOP legislators to pass no new taxes. As state services were threatened and the public began to show its resentment, Democrats searched for the single Republican vote they needed to pass the budget, which required a two-thirds majority. They turned to Maldonado, who was a moderate Republican.

Maldonado agreed to align himself with the Democrats, if they would help advance the implementation of the top-two primary in return. The system appealed to Maldonado as a result of his experience in his district, which was almost evenly split between Republicans and Democrats. Maldonado had come up through the political ranks convinced of the need to appeal to both sides, and he knew the benefit this brought to politics: moderate candidates who knew how to work with other party. The gridlock in the California legislature over the budget provided the opportunity Maldonado had been looking for.

“Why would I vote for a budget that had temporary tax increases, and some other things that I really didn’t like?” he said. “Why would I vote for something without a piece of reform that would change California, and in the future not have these long stalemates in the budget process?” Maldonado recalls Democrats trying to pass the budget on their own, and then tapping him for help when they couldn’t get the number of votes they needed.

The legislature agreed to vote to put a measure on the ballot in June 2010 that would contain several election reforms—including an open primary with the top-two mechanism. But, to amend the state’s constitution, Maldonado’s proposal had to be passed by voters. It initially seemed unlikely that they would endorse it, as his proposal set off a storm of indignation and outrage. Many politicians felt Maldonado had held the budget process hostage to get his proposal through. But voters passed the proposal by a 54 to 46 margin. And after a subsequent legal challenge, the top-two primary made its debut in 2011.

One of the immediate impacts of the top-two primary was that it had inadvertently created an incentive for candidates to broaden the field, recruiting additional candidates to dilute support for their most dangerous opponents. This became evident in the 2014 congressional race between Mike Honda and Ro Khanna.

Honda had been representing Silicon Valley in the U.S. House of Representatives since 2001, frequently voting with his Democratic colleagues and toeing the party line. (His 2014 campaign headquarters was even located inside the Service Employees International Union headquarters.) Honda had celebrated many successes in the predominately Democratic state, winning reelection in 2012 with 73 percent of the vote.

Two years later, Khanna, an Obama appointee, challenged Honda. He positioned himself as the modern Democrat—a pro-business candidate who would represent his district’s technology interests in Washington. If Khanna could make it to the general election, the thinking went, he could get enough independent and Republican votes to win. But to get to the runoff, Khanna needed to get more votes than the Republican candidate, Vanila Singh.

A lawsuit filed in 2014 alleged that Khanna “recruited candidates to enter the race as Republicans to split the Republican vote three ways, effectively diluting votes that would otherwise be cast in favor of Singh.” Shortly before the filing deadline, Vinesh Singh Rathore and Joel Vanlandingham, two Republican candidates, entered the race. The suit also alleged some of those who had signed the candidates’ petitions were supporters of Khanna.

High drama ensued. A lawsuit was filed to throw both last-minute GOP candidates off the ballot and a judge tossed the candidacy of Rathore because of a problem with his signatures. The law firm that brought the lawsuit was Dhillon & Smith. One partner at the firm, Harmeet Dhillon, was also the vice chairwoman of the California Republican Party. In short, Democrats were trying to get Republicans to run against Democrats, only to get stopped by a leading Republican.

Maldonado defends the top-two primary, but is also not surprised by how it has unfolded. “It’s people trying to twist the election process. They have done that in the past. Prior to the open primary, and through the open primary,” he told me.

That appeared to be the case in 2015 in the 7th State Senate District, a quiet suburb of the San Francisco Bay Area. When the district’s Democratic state senator, Mark DeSaulnier, was sworn in to succeed Representative George Miller in Congress, Governor Jerry Brown called a special election to fill DeSaulnier’s seat. Susan Bonilla, a Democratic assemblywoman, was eyeing the state senate. Bonilla had the backing of the entire Democratic machine, with a pack of endorsements and the financial backing of the unions. It looked like a layup.

Orinda Mayor Steve Glazer entered as a centrist Democratic candidate, running alongside Republican candidate, Michaela Hertle. Glazer’s candidacy posed a threat to Bonilla. The large percentage of Republican voters in the district gave an advantage to the more-moderate Glazer, and it only became more pronounced when Hertle suddenly pulled from the race and pledged her support of him. Voters visiting Hertle’s campaign website found a message reading, “Vote for Steve Glazer.” Suddenly, Bonilla was in trouble—a Democrat about to get taken out by another Democrat with the help of Republican voters.

Hertle’s exit from the race was a surprise. And then, just before the election, a flyer appeared on the doorsteps of voters in District 7 telling them to vote for her because she’s “a real Republican,” in an apparent effort to trick voters into casting ballots for a candidate who was no longer running. It was the Asian American Small Business PAC trying to pull a Weekend at Bernie’s move. The California Republican Party (which had not endorsed any candidate in the race) filed a trademark infringement complaint because the flyers had the Republican elephant on them.

The open primary continued to tilt in Glazer’s favor. Despite opposition from Glazer’s former allies in the Democratic Party, Glazer made it through the primary (though Hertle got 16 percent of the vote to Glazer’s 33.7 percent), and trounced Bonilla by nine points in the general election.

Maldonado told me he believes that without the introduction of the open primary, Glazer would not be a senator in California. According to him, Bonilla would have ridden the Democratic rails into office, greased with a large Democratic voting block, a slew of party endorsements, and the backing of organized labor. But the top-two primary gave the independent and Republican voters the chance to influence a Democratic race in ways the Democratic establishment seemingly couldn’t process.

Maldonado revels in the fact that the conservative members of the Republican Party, who might have never seen the inside of a Democratic legislator’s office, now have to think about working with them. And the same is true for Democrats, who now have to reach out to not just Republicans, but independents and voters who aren’t affiliated with any party.

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Christopher Caen is a writer based in San Francisco. He has covered California politics for almost two decades.